Method of sealing a bag and a bag sealing apparatus

ABSTRACT

The invention provides a method of sealing a bag ( 8 ) comprising (a) gripping the neck ( 10 ) of the bag ( 8 ) (b) passing the gripped portion of the bag neck ( 10 ) around a rod ( 6 ) approximately a complete revolution (c) continuing to revolve the gripped portion of the bag and moving the gripped portion axially away from the distal end of the rod ( 6 ) until generally a further 2-300 degree revolution has been completed so that the neck ( 10 ) of the bag ( 8 ) is wrapped around the rod ( 6 ) (d) opening a recess ( 14 ) in the rod and placing the free end of the neck ( 10 ) into the recess, and (e) holding the free end in the recess ( 14 ) whilst withdrawing the rod ( 6 ) through the wrapped portion of the neck. The invention also provides apparatus for carrying out the method.

This invention relates to the sealing of bags such as bags for containing meat or agricultural produce such as root crops.

Conventionally, bags are sealed using stitching (for bags made from woven material) or welding techniques (for plastics bags). These methods are effective in sealing; however, these methods create problems when the bag must be opened.

Typically, the prior art bags are opened using a knife or other sharp implement. This creates the risk of injury to personnel opening bags and under certain safety regimes is prohibited. Further alternatives include using additional material to tie around the neck of the bag or placing a knot in the neck of the bag. The former solution has the disadvantage of requiring extra materials, either associated with the bag on sealing or attached to the bag, and furthermore requires a manual tying operation. The latter solution also requires a manual tying operation. Accordingly, although these two solutions remove the need for cutting implements to be used to open the bags, they are expensive to implement through the requirement for additional materials or manual operations.

In accordance with a first aspect of the present invention there is provided a method of sealing a bag comprising gripping the neck of the bag; passing the gripped portion of the bag neck around a rod approximately a complete revolution; continuing to revolve the gripped portion of the bag and moving the gripped portion axially away from the distal end of the rod until generally a further 2-300 degree revolution has been completed so that the neck of the bag is wrapped around the rod; opening a recess in the rod and placing the free end of the neck into the recess, and holding the free end in the recess whilst withdrawing the rod through the wrapped portion of the neck.

In a second aspect, there is provided a bag sealer comprising a rod, a gripping arm rotatable about the rod, preferably concentrically with the rod, the gripping arm and rod being movable relative to one another in an axial direction, the gripping arm including jaws or the like, operable to grip the neck of a bag to be fastened, and the rod including a coverable recess arranged to accept a portion of a bag neck when opened and to generally be flush with the outer diameter of the rod when closed.

An embodiment of the invention will now be described by way of example with reference to the drawings in which:

FIG. 1 is a side view of the apparatus in accordance with the invention in a first stage of operation;

FIG. 2 is a side view of the apparatus in accordance with the invention in a second stage of operation;

FIG. 3 is a side view of the apparatus in accordance with the invention in a third stage of operation;

FIG. 4 is a side view of the apparatus in accordance with the invention in a fourth stage of operation;

FIG. 5 is a side view of the apparatus in accordance with the invention in a fifth stage of operation;

FIG. 6 is a side view of the apparatus in accordance with the invention in a sixth stage of operation;

FIG. 7 is a side view of the apparatus in accordance with the invention in a seventh stage of operation;

FIG. 8 is a side view of the apparatus in accordance with the invention in an eighth stage of operation;

FIG. 9 is a side view of the apparatus in accordance with the invention mounted on a moving track;

FIG. 10 is a section along the line X-X of FIG. 9; and

FIG. 11 is an end view of the apparatus in FIG. 9.

With reference to FIG. 1, a grab arm 2 has jaws 4 located at its distal end. The jaws 4 are rotatable on the end of the grab arm as will be described later.

The grab arm is rotatable about a rod 6. As drawn, the grab arm rotates concentrically with the rod but this is not essential.

With reference to FIG. 2, a bag 8 may be introduced beneath the rod and grab arm as described in more detail later. It will be appreciated that although the rod and grab arm are shown in a horizontal orientation with a bag neck 10 generally at 90° to the apparatus, the apparatus may be orientated differently in respect to the bag and may, for example, be orientated vertically. Generally, of course, the bag will be located below the apparatus to avoid spillage of content during the sealing operation.

The bag may be introduced to the apparatus using conventional means although a detailed explanation is given below.

With reference to FIG. 3, the jaws 4 are operated to grip the neck of the bag and the grab arm 2 is rotated nearly a complete revolution about the rod 6, thus wrapping the neck of the bag 10 about the rod. At the same time, the jaws are retracted back from their extended position in order to draw the neck of the bag 10 back towards the apparatus away from the bag 8.

With reference also to FIG. 4, the grab arm 2 then continues to revolve around the rod 6 until typically a further two to three hundred degrees of revolution have been completed. At this point, the bag neck 10 is looped nearly two complete revolutions around the rod 6.

With reference to FIG. 5, a latch 12 uncovers a recess 14 in the rod 6. The jaws 4 are then extended to place the neck of the bag 10 into the recess 14 followed by closure of the latch 12. This is shown in FIG. 6 with the jaws now rotated approximately a further quarter revolution to be in front of the rod 6 in the plane of the drawing.

With reference to FIG. 7, the jaws 4 may now release the neck of the bag and may be moved out of the way (it will be noted that the grab arm 2 is no longer shown in FIG. 7 since its operation is complete).

The rod 6 may now retract, pulling the end of the bag through the double looped portion of the neck. The double looped portion of the neck 16 is prevented from sliding back up the rod by an annular collar 18. As the rod 6 withdraws, the neck is pulled through the double looped portion 16, thus forming a knot. The bag is now sealed and may be opened by unknotting without the use of cutting tools.

It will be appreciated that the above may be implemented using pneumatic or hydraulic technology, and using components which have been well tested in a factory environment. The apparatus provides a convenient and repeatable bag sealing function and may be adjusted to suit different size bags, for example by providing a micro-controller to operate the hydraulic/pneumatic rams and by reprogramming the micro-controller.

With reference to FIGS. 9 to 11, the apparatus is shown mounted adjacent a moving powered track. Each bag is introduced to the apparatus and the neck of the bag 10 is held upright using a powered moving track 20 which both grips the neck of the bag and allows it to be passed along at the same rate as a moving conveyer 22.

As the bag 8 moves beneath the apparatus, the bag is held stationary while the knotting operation is performed. The powered track 20 and conveyer 22 may then operate to move another bag beneath the apparatus so that knotting may be carried out as part of an automated sequential operation, for example on the same conveyer used to fill the bags. 

1. A method of sealing a bag comprising (a) gripping a neck of the bag; (b) passing a gripped portion of the bag neck around a rod approximately a complete revolution; (c) continuing to revolve the gripped portion of the bag and moving the gripped portion axially away from a distal end of the rod until generally a further 2-300 degree revolution has been completed so that the neck of the bag is wrapped around the rod (d) opening a recess in the rod and placing a free end of the neck into the recess, and (e) holding the free end in the recess whilst withdrawing the rod through a wrapped portion of the neck.
 2. A method according to claim 1, including holding an annular collar formed around the rod, generally stationary against an edge of the wrapped portion of the neck to cause the wrapped portion to be removed from the rod when the rod is withdrawn.
 3. A bag sealer comprising a rod, and a gripping arm rotatable about the rod, preferably concentrically with the rod, the gripping arm and rod being movable relative to one another in an axial direction, the gripping arm including jaws operable to grip a neck of a bag to be fastened, and the rod including a coverable recess arranged to accept a portion of a bag neck when opened and to generally be flush with an outer diameter of the rod when closed. 